How to upgrade my manual central locking system of my Hyundai i20 magna to remote locking system?

i believe the hyundai is very similar to the Kia, depending on which model it is, but on the base models without elec windows and remote central locking you would have to fit and wire up a central locking receiver or universal central locking system, a central locking motor into the drivers door (the kia only has a switch which sends a signal to lock and unlock the rest of the doors) and would have a extra remote to attach to your keys to work the system.

If the same car was also offered with remote central locking as an option then you may be able to purchase and fit the required parts to retrofit the feature.

This would essentially give you the neatest solution that would make it for all intents and purposes as if the car had always had the option selected. This may not be possible however or getting the parts from Hyundai may be prohibitively expensive.

Another option would be to fit a third party kit to do the same job, something like the Viper 211HV can be purchased for a relatively low cost and if you're feeling brave (or know someone who is handy with wiring) can even be fitted at home (NB: I believe the warranty on these is only valid if you have an authorized dealer fit them so a DIY fit is at your own risk!)